Apparatus for applying ring-shaped markings to electric current conductors



Nov. 14, 1967 G. BUHMANN APPARATUS FOR APPLYING RTNG-SHAPED MARKINGS TO ELECTRIC CURRENT CONDUCTORS Fig.4

. Filed April 6, 1965 United States Patent 3,352,285 APPARATUS FDR APPLYING RING SHAPED MARKINGS T0 ELECTRIC CURRENT CON- DUCTORS Gunther Buhmann, Ludwigsburg, Germany, assignor to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 6, 1965, Ser. No. 446,065 Claims priority, application Germany, June 2, 1964, St 22,248 8 Claims. (Cl. 118-624) ABSTRACT OF THE DISCLOSURE Annular color coded markings are applied to a conductor by feeding it through a coaxial tube having longitudinally disposed radially directed tapered electrodes. Tubular sections which mask portions of the conductor not to be color coded are positioned in spaces between adjacent electrodes. A spray of colored material is introduced through the electrodes which charge the particles and apply a potential difference between the tube and conductor to deposit the particles on annular longitudinal areas.

The present invention deals with the colored or contrasting identification of electric current conductors. The term electric current conductors is intended to refer to bare conductors as well as to insulated conductors. The invention is of a particular importance to the marking or identification of insulated conductors whose insulation consists of plastic materials. These plastic materials may include such ones as vinylpolymers. However, it is also possible to use polyolefins, hence e.g. polyethylene or polypropylene.

In connection with applying colored code markings to such types of insulated conductors there often arises the difliculty that the adhesion of the color particles on the surface of the insulating material is insufiicient. In order to improve the adhesion of the marking or code color on the surface of the insulating material, quite a number of proposals have already been made, chiefly relating to the activation of the surface of the insulating material. This activation is carried out in the most different ways. Thus, for example, it has been proposed amongst others, to heat the surface, or to treat the surface with a gas flame, and finally there have become known quite a number of methods according to which the surface can be activated by treatment with chemicals. Such an activation of the surface of the insulating material may thus, if so required, be used as thebasis of the inventive method.

In the cable field the marking of insulated conductors has been long known. In the present case the marking is intended to be applied to the surface of the insulating material. Also this kind of marking of electric conductors is known, but conventional methods chiefly dealt with the application of helical markings to the insulating materials. In the conventional methods for applying helical markings an inking element is mostly led around the conductor, so that there is produced a helical or spiralshaped pattern. These conventional methods, however, were unable to provide ring-shaped or annular markings or color codes. For the marking or identification of such insulated leads it has already become known to use printing rollers which are moved or pulled over the conductor, and with the aid of which the conductors can be printed with ink by way of correspondingly coloring the circumference of the printing roller. In this way it is possible to apply letters or numerals to the insulated sheathing. It is conceivable without further ado, that in this way also dashes or straight lines extending vertically in relation to the conductor axis, may be imaged or printed upon the 3,352,285 Patented Nov. 14, 1967 insulation, and that these dashes or lines, due to the shape of the circumference of the printing roller adapted to the insulation (sheathing), may also extend over almost half the circumference of the conductor. In this case, however, there is required at least a second such type of printing roller for completing the marking or identification dash or line extending over half the circumference, also on the other side or half of the circumference of the conductor. Irrespectively of the fact that with this type of marking method it is impossible to produce a closed ring or annular code, there are required several such printing rollers which, in addition thereto, for the purpose of applying the semicircular marking dashes or lines in the same plane, must be in synchronization with one another. This relatively simple way of applying annular color codes or markings to electric conductors, however, is no longer suitable for being used under the present high-speed manufacturing conditions, amounting to e.g. several hundred meters of insulated conductors per minute, because in that case the printing rollers will not only have to be provided with driving systems of'their own, but also the ink supply would have to be adapted to the extremely high speed of manufacture.

From the lacquer field there has now become known the electrostatic method of applying paint.

According to this method an atomized spray of lacquer or paint is maintained over the metal surface on which the coat of lacquer or paint is to be applied, and between the metal surface and the metallic atomizer nozzle there is applied a high-voltage potential. The charged color particles, due to the electrostatic attraction, are now guided onto the metal surface upon which they impinge with a considerable speed. This method, for example, is often used for applying coats of lacquer to the bodies of motor vehicles.

In the cable manufacturing field the electrostatic method of applying paint or lacquer has likewise already been used. According to the German Patent No. 1,125,026 it is proposed to guide the insulated conductor in a freely suspended manner through a metal cylinder which, in its inside, is provided with spikes directed to the axis of the metal cylinder. Through a longitudinal slot provided on the side of this metal cylinder, the latter is supplied with vaporized (atomized) or sprayed color particles. Between the passing conductor and the metal cylinder with its spikes, there exists a high-voltage potential on account of which the color particles are guided onto the surface of the conductor insulation. This arrangement, however, enables an equal color application to the whole surface of the insulation, but it is in no way suitable for providing a ring-shaped (annular) marking or identification on the conductor.

Since with the conventional means, it is impossible to provide an unobjectionable high-speed annular code marking, especially with sufficiently sharp contours, on electrically insulated lines or conductors, the present invention proposes a method of effecting the continuous, especially high-speed color coding (marking, identification) of a bare or insulated electric current conductor with the aid of an electrostatic precipitation of a sprayed or vaporized (atomized) color mixture and/ or color solution (ink solution) along a path traversed by the conductor. The precipitation is kept in a suspended condition with a highvoltage difference existing between the e.g. grounded conductor and the electrode preferably surrounding the conductor in a ring-shaped manner. This method is particularly characterized in that for producing a succession of colored code rings of sufficiently sharp contours, the ring surrounding the conductor as an electrode, is very short, and is provided with conducting spikes directed towards the inside and to the passing conductor, and that the high voltage producing the electric wind at the spikes towards the radially and inwardly directed acceleration of the color particles, produces a succession of impulses, preferably of rectangular impulses, and is thus effective, and whose timed relation is adjustable for adjusting the spaced relation, depending on the pulse spacing, of the marking or color-code rings on the conductor.

Accordingly, it is proposed by the present invention to design a very short metallic, annular electrode provided with inwardly directed spikes, hence eg in a ring-shaped manner, so that upon application of a high-voltage difference to a conductor imagined to be standing still, there Will be produced a relatively sharply contoured ringshaped code marking on the surface of the conductor. However, if the conductor is pulled at a relatively high speed through the ring provided with the spikes, it will be possible to produce subsequently following code marking rings if for each intended code marking ring, a highvoltage pulse is caused to act upon the suspending color particles. At a high pulse repetition rate of frequency, therefore, the code marking rings will have to have a small spaced relation, and the pulse repetition rate of frequency will have to be slowed down in cases where a greater spaced relation is desirable, hence, in other words, the time elapsing between the individual pulses will have to be extended. Of course, particularly suitable to this end are pulses with steep as possible edges, hence above all the so-called rectangular pulses. These pulses can be easily produced with the aid of electronic switches of any arbitrary duration and amplitude, and in this way the pulses may also be regulated (controlled).

In such an arrangement the vaporized (atomized) or sprayed color particles are slowly led to the spikes of the ring-shaped electrode within a suitable tubular guide member.

Since at the spikes there exists an excessive amount of electricity carriers of one sign, and since these diverge from the point of the spikes ,the friction causes molecular air current to be taken along thereby, resulting in the so-called electric wind. The suspending color particles are accelerated by this electric wind extending from the points of the spikes, and are conveyed in direction to the conductor upon which they impinge in accordance with the increasing speed, and adhere well.

According to this method, however, only a relatively small amount of color particles can be conveyed and applied. In many cases the color code or application achievable thereby, will prove to be insufficient. The invention method, therefore, may be further embodied in that for the purpose of increasing the thickness of the color code applied by one electrode, several such electrodes can be arranged and operated by being disposed coaxially in series.

The electrodes arranged at an equally spaced relation, are electrically connected to one another, and are acted upon by the high-voltage pulses. Hence, the insulated conductor enters the arrangement at the first electrode and is there provided with its first relatively thin color code during the time of the. impulse. During the time Where the conductor is not acted upon by pulses, the conductor is advanced by a small length, and, by the action of a further pulse, is supplied or coated with color particle's upon reaching the second annular electrode. At the same time, under the first annular electrode, and by the action of the same pulse, there is ettected the first color application of the next annular code marking. The color application under the second ring or annular electrode is naturally already relatively more intensive. In this way the conductor passes through a number of such annular electrodes which, upon passing through of the annular marking, are exactly acted upon by the high-voltage pulse on account of which a corresponding number of color particles are precipitated on the insulation of the conductor. In this way it is possible to provide the color code with any desired intensity or distinction.

FIG. 1 schematically shows one such color coded conductor. The insulated or bare conductor 1 carries on its surface 2 the annular markings (color codes) 3. The length of the annular marking is designated by the reference S and the spacing between the annular markings is designated by the reference 5 The entire section consisting of S and S is indicated by the reference a.

The non-coded sections of the conductor will remain free from color particles. For this reason it is a necessity to reliably prevent the color particles which are in the suspended state, from being applied to the conductor surface during a time in which a high-voltage pulse is not effective. Since the color particles also retain their charge after termination of a high-voltage pulse, and are thus ionized, it is necessary to apply a potential difference during the time in which no pulse is effective, to the conductor on one hand, and to the annular electrode provided with spikes, on the other hand, thus causing the suspending and charged color particles to reverse their direc tion of movement towards the conductor, or at least to cause them to come momentarily to a standstill. This may be accomplished in that the high-voltage pulses are superimposed upon a relatively high direct voltage. Hence, during the time in which no pulse is effective, the DC. voltage will act in such a way that the charged color particle is either retarded, stopped, or reversed in its radially inwardly directed movement. This process merely needs to take place in the close proximity of the conductor surface which is to be acted upon. In this way, by correspondingly selecting the amplitude and polarity of the DC. voltage, as well as of the high-voltage pulses, color particles can be prevented from being deposited on the sections which are not intended to be provided with color code markings.

Hence, with respect to the sections not to be provided with color codes, the trend of the charged color particles is directed away from the conductor, and the particles are merely transported to the conductor during the time in which the correspondingly high voltage pulse is caused to act upon the conductor.

In order to still further increase the sharp contours of these annular markings, the invention is further embodied in that between the electrodes provided withthe spikes which, of course, may be combined to form one unit by employing a tube (tubular section), and the passing conductor, there is arranged a mask (template), as shown in FIG. 2. This mask has the shape of a tube provided with cuttings or indentations arranged at a spaced relation corresponding to that of the annular code markings. The length of the individual tubular sections corresponds to the length of the sections not to be provided with color codes on the conductor, as shown in FIG. 1 at point S The spacings existing between the tubular sections correspond to about the length of the annular code marking shown in FIG. 1, hence to the length S The individual tubular sections are in such a way retained in their position that the color application is not or not substantially disturbed by this holding arrangement. This mask consisting of tubular sections, is disposed relatively closely over the conductor, and the ring-shaped electrodes provided with sp1kes, are positioned exactly in front of the slots provided in the mask, so that the color particles taken along by the electric wind of the spikes, are capable of being applied to the conductor through the holes in the mask. Relative thereto the mask apertures serve to clip or restrict the more orless straying current or flow of color particles extending from the spikes, in a ring-shaped manner. By suitably selecting the width of the slots in the mask it is possible to achieve a marking of very narrow annular color codes.

In FIG. 3 this inventive arrangement is shown in a schematic representation. The conductor 1 is passed through the metal cylinder 6 provided with the spike ringsS. Closely above the conductor 1 there is arranged a tubular mask 7. It will beeasily recognized that the spikes, the slots of the mask, and the annular code markings are in one plane on the conductor, or are arranged symmetrically in relation thereto, respectively.

In the example of embodiment shown in FIG. 3 the vaporized color spray is substantially supplied within the tubular electrode 4. However, the application of the vaporized color spray may also be effected in that the points of the spikes are provided with concentrical bores (holes) 13 thus acting as atomizer nozzles for supplying the vaporized (atomized) spray from the outside therethrough to the points of the spikes, and is there seized by the electric wind. Moreover, the supply of vaporized spray may also -be accomplished in that borings 14 are provided next to the basis of the spikes in the tubular electrode, so that the vaporized spray will be applied from the outside through these borings into the tubular electrode, for being seized by the electric wind at the sides of the spikes. In this case it will be appropriate to provide a further supply tube 15 for the vaporized color spray, concentrically surrounding the tubular electrode. In this case it will avoid unnecessary depositions of vaporized color spray within the tubular electrode, and especially on the mask.

The tubular mask 7 in FIG. 3 may consist of an insulating material. To this end it is advisable to use e.g. polytetrafiuoroethylene which is highly resistant to heat and solvents. In cases where the mask is made of an insulating material, the electric field driving the stream or flow of color particles, may be focused.

However, the mask 7 in FIG. 3 may also consist of metal, and may be electrically charged similar to the grid of an amplifier tube. This charge may have an opposite polarity to the charge of the vaporized color particles. In this case the vaporized spray particles would be accelerated. The charge of the metal mask, however, may also correspond to that of the color particles, so that then the color particles would be repelled. In this way it can be accomplished that the vaporized color spray particles are moved from the spikes, in a pilgrim-step manner, in direction towards the conductor, in other words, that the vaporized color spray particles are moved once comparably to longitudinal units in direction towards the conductor, and then by each time one unit in the backward direction.

On account of this there is caused a trend of the vaporized particles in direction towards the conductor which, however, is always interrupted by the pulsating field between the conductor and the electrode tubing, when the portions or sections of the conductor which are not supposed to be colored, are moved past and below the slot of the mask.

It is also possible to apply a variable D.C. voltage field between the conductor and the point or spike electrodes, and to impress a pulsating voltage upon the metal mask, so that the metal mask will then act as an electrostatic control element.

If the vaporized color spray particles are only moved during a short time interval t towards the conductor, and are either not moved at all, or even somewhat away from the conductor during a second time interval t then the sum of these time intervals, at -a passing speed v of the conductor, will correspond to the longitudinal sections S +S =a according to FIG. 1.

In cases where the color-free interval on the conductor is equal to the interval during which a color marking is to be applied, it is also possible to employ an alternating voltage instead of the pulsating voltage. The manufacturing speed of the conductor is v=a/t. Accordingly, the proper pulse frequency would thus be f=1/t=v/a.

For example, if a=15 mm., and if the passing or travelling speed amounts of 360 meters per minute, then the necessary pulse frequency would be 400 c.p.s.

In cases where the dimensions of the annular color codes and their spaced relations are to be changed, it is possible, of course, to exchange the tubular mask and the spike electrodes.

To ensure a proper functioning of this arrangement it is of importance to provide the correct high-voltage pulse waveform. If possible, the pulses should have a rectangular waveform according to FIG. 4. The width b of the pulses should correspond to the width of the ring S The pulse interval a should correspond to the non-colored conductor section S The pulse voltage U should be as high as possible in order that the vaporized color particles can be applied as quickly as possible to the conductor surface at the desired time position. 0n the other hand, it must be avoided that color is applied to the conductor during the remaining time between the pulses. This is best effected by way of a polarity reversal, in that an opposite D.C. high voltage U is superimposed upon the pulse voltage. An arrangement for producing these voltages is shown in FIG. 5. The generator 8 produces the rectangular pulses which are stepped up to a high voltage with the aid of the transformer 9. This high voltage is then applied on the secondary side to the conductor 1 which is grounded at point 12, whereas the harmonic voltage side, as already described hereinbefore, may be applied to the spike electrodes or the metallic tubular mask respectively. In this circuit a D.C. source 10 is arranged in such a way that both voltages are superpositioned. The voltage U which, according to FIG. 4, is applied between the high-voltage pulses, has an opposite sign with respect to the now effective pulse amplitude U and thus prevents the color particles from being deposited on the surface of the conductor.

Thus, in order to produce a continuous color stream towards the conductor, U must always be greater than U By variably designing U and U it is possible to achieve an optimum production of annular color codes.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. Apparatus for providing continuous high speed annular color coding of a conductor comprising means to move said conductor along a predetermined path, a tube member coaxial with said conductor, spray producing means to introduce particles of coloring matter into said tube and surrounding said conductor, a plurality of tubular sections spaced apart a distance equal to the width of the color code, said tubular sections being disposed within said tube member and surrounding said conductor to mask portions of said conductor not to be color coded, a plurality of electrodes for charging said particles and means to provide a potential difference between said tube and said conductor for deposition of said particles on the surface of said conductor, said electrodes being disposed on the inside surface of said tube member, each electrode comprising a group of tapered members annularly disposed and each having channels radially directed towards said conductor through which said colored material is introduced within said tube member, each said electrode being disposed adjacent a space between said tubular sections.

2. Apparatus according to claim 1 wherein said means to provide a potential difference comprise pulse generating means and means connecting the output of said pulse generating means to said electrodes and said conductor.

3. Apparatus according to claim 2 wherein in the case of an equal spaced relation of the colored code markings said electrodes are arranged in series in accordance with the distance between ring-shaped color codes, and means to couple to said electrodes pulses of the same phase relation.

4. Apparatus according to claim 3 wherein said pulses are superimposed upon a D.C. voltage and said D.C. voltage has an opposite polarity to said pulses.

5. Apparatus according to claim 1 wherein said masking means comprise polytetrafluoroethylene.

6. Apparatus according to claim 1 where said masking electrostatic control element with respect to the flow of 1 color particles.

8. Apparatus according to claim 6 wherein the flow of color particles with the aid of a DC. voltage having an opposite sign with respect to the color particles, is moved between the conductor and the electrodes in a pilgrimstep manner towards the conductor.

8 References Cited FOREIGN PATENTS r 222,198 7/ 1962 Austria. 0 1,125,026 3/1962 Germany. 1,134,129 8/ 1962 Germany.

121,161 1959 U.S.S.R.

10 CHARLES A. WILLMUTH, Primary Examiner.

PETER FELDMAN, Assistant Examiner. 

1. APPARATUS FOR PROVIDING CONTINUOUS HIGH SPEED ANNULAR COLOR CODING OF A CONDUCTOR COMPRISING MEANS TO MOVE SAID CONDUCTOR ALONG A PREDETERMINED PATH, A TUBE MEMBER COAXIAL WITH SAID CONDUCTOR, SPRAY PRODUCING MEANS TO INTRODUCE PARTICLES OF COLORING MATTER INTO SAID TUBE AND SURROUNDING SAID CONDUCTOR, A PLURALITY OF TUBULAR SECTIONS SPACED APART A DISTANCE EQUAL TO THE WIDTH OF THE COLOR CODE, SAID TUBULAR SECTIONS BEING DISPOSED WITHIN SAID TUBE MEMBER AND SURROUNDING SAID CONDUCTOR TO MASK PORTIONS OF SAID CONDUCTOR NOT TO BE COLOR CODED, A PLURALITY OF ELECTRODES FOR CHARGING SAID PARTICLES AND MEANS TO PROVIDE A POTENTIAL DIFFERENCE BETWEEN SAID TUBE AND SAID CONDUCTOR FOR DEPOSITION OF SAID PARTICLES ON THE SURFACE OF SAID CONDUCTOR, SAID ELECTRODES BEING DISPOSED ON THE INSIDE SURFACE OF SAID TUBE MEMBER, EACH ELECTRODE COMPRISING A GROUP OF TAPERED MEMBERS ANNULARLY DISPOSED AND EACH HAVING CHANNELS RADIALLY DIRECTED TOWARDS SAID CONDUCTOR THROUGH WHICH SAID COLORED MATERIAL IS INTRODUCED WITHIN SAID TUBE MEMBER, EACH SAID ELECTRODE BEING DISPOSED ADJACENT A SPACE BETWEEN SAID TUBULAR SECTIONS. 